Developmental delay is term used when children are significantly delayed in their cognitive (concerned with the act or process of knowing) and physical development (Pic. 1). There is usually a more specific condition which causes this delay, such as chromosonal abnormalities (a missing, extra, or irregular portion of chromosomal DNA). However, it is sometimes difficult to identify this underlying condition. Developmental disabilities can be detected early on, and do persist throughout an individual's lifespan.

Other terms associated with this condition are failure to thrive (which focuses on lack of weight gain and physical development), intellectual disability (which focuses on intellectual deficits and the changes they cause to development) and developmental disability (which can refer to both intellectual and physical disability altering development).

Developmental disabilities cause individuals living with them many difficulties in certain areas of life, especially in "language, mobility, learning, self-help, and independent living". 

Signs of developmental delay are different from one age group to another. Examples include:

1-3 months

  • not responding to loud noises
  • not following objects with eyes
  • not looking at parents

4 months

  • not making eye contact
  • not making sounds
  • not mouthing objects
  • 6 months
  • not rolling
  • not babbling
  • not smiling or showing emotions

12-15 months

  • not crawling
  • not using single words
  • not using gestures like waving or pointing

2 years

  • not running
  • not using 2 words together
  • not copying actions or words

3 years

  • not drawing
  • problems with speaking clearly
  • not interested in other children

The specific cause of developmental delay is often unknown. Causes may include:

  • complications at birth (e.g. premature birth, birth deficient supply of oxygen to the body)
  • complications after birth (e.g. jaundice)
  • brain trauma or abnormal brain structure
  • chromosome abnormalities (e.g. Down syndrome)
  • disorders (e.g. autism spectrum disorder, fetal alcohol spectrum disorder)
  • syndromes (e.g. Klinefelter syndrome)
  • encephalitis (swelling of the brain)
  • malnutrition, lack of medical care.

Diagnosis and assessment can enable access to early intervention services provided by physiotherapists, occupational therapists, speech therapists and specialist teachers who work with parents and children to help develop skills in movement, coordination, communication and play.

Developmental delay is associated with Klinefelter syndrome, which has severe impact on fertility.

Klinefelter syndrome (KS)

The term Klinefelter syndrome describes a group of chromosomal disorders in which there is at least one extra X chromosome (Pic. 2) to a normal male karyotype, 46,XY. Some males with Klinefelter syndrome have the extra X chromosome only in some of their cells (mosaic Klinefelter syndrome).

As babies and children, XXY males may have weaker muscles and reduced strength. Also they have hypospadias (the urethra where the urinary opening is not at the usual location on the head of the penis), small penis or cryptorchidism (undescended testicles) and developmental delay. 

As they grow older, they tend to become taller than average. They may have less muscle control and coordination than other boys of their age. The older child or adolescent may be discovered during an endocrine evaluation for delayed or incomplete pubertal development with eunuchoid body habitus, gynecomastia, and small testes.

Although most patients with Klinefelter syndrome are infertile, there have been a few patients with reports of pregnancy without assisted medical technology, typically in mosaic cases. With the introduction of intracytoplasmic sperm injection, which involves the use of sperm extraction from deep within the testicles of patients with non-mosaic Klinefelter syndrome, some XXY men will have an increased chance of fathering a child.

Find more about related issues


KLINEFELTER SYNDROME ―sourced from licensed under CC BY- SA 4.0
Developmental delay ―sourced from Queensland Government licensed under CC BY 3.0
Global developmental delay ―sourced from Wikipedia licensed under CC BY- SA 3.0
Developmental disability ―sourced from Wikipedia licensed under CC BY- SA 3.0
Diagnosing motor developmental delay in children under 6 ―sourced from Wikispaces licensed under CC BY- SA 3.0
Human chromosomesXXY01 ―by Nami-ja licensed under CC0
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